Youngest pope, oldest pope Pope John XII was just 18 when he was elected in 955. The oldest popes were Pope Celestine III (elected in 1191) and Celestine V (elected in 1294) who were both nearly 85.

That is where the name still used for the process of selecting a new pope — "conclave," which translates to "under lock and key" — came from. After that marathon conclave, Pope Gregory X was ...

His successor, Pope Gregory X, was elected in 1271. Pope Francis, however, was elected in 2013 on the fifth ballot, while his predecessor, Benedict XVI, ascended after four rounds in 2005.

Pope Gregory X was finally elected in September of 1271 after about 1,000 days. Haley Ott contributed to this report. More from CBS News. Sen. Thom Tillis announces he won't seek reelection.

The previous pope, Pius X, had mandated in 1904 that all papers related to the election, not just the ballots, be burned, "thus producing a great deal more white smoke for the final ballot and ...